(a) Field of the Invention
The present invention relates to an automatic transmission, and more particularly, to a power train of an automatic transmission.
(b) Description of the Related Art
A multi-stage gearshift mechanism of an automatic transmission includes a plurality of planetary gear sets. A power train having such a plurality of planetary gear sets varies the torque in multiple stages and outputs it to an output shaft when receiving a converted engine torque from a torque converter.
The more speeds the power train of an automatic transmission has, the better the power performance and fuel consumption. Therefore, it is desirable for power trains to have as many speeds as possible.
For the same number of speeds, durability, power transmission efficiency, and size/weight of a transmission are substantially dependent on how the planetary gear sets are arranged.
For a manual transmission, too many speeds cause a driver the inconvenience of excessive manual shifting. However, for an automatic transmission, a transmission control unit automatically executes shifting by controlling the operation of the power train, and therefore, more speeds usually implies more merits.
Accordingly, recently, a power train of an automatic transmission enabling six forward speeds and one reverse speed has been developed.
However, according to the conventional power train, because the clutches and the brakes are disposed to a back of the transmission, an operating hydraulic line is difficult to be formed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.